Sulfo-group-containing heat-resistant high-molecular material and a preparation process thereof

ABSTRACT

Disclosed herein is a sulfo-group-containing heat-resistant high-molecular material containing sulfo groups in an amount of not less than 1 wt. % in terms of sulfur content and having an ammonia adsorptivity of not less than 10 mg/g, formed by heat-treating at a temperature of 250°-500° C. a starting composition composed mainly of a sulfo-group-containing aromatic high-molecular compound which comprises unit constituents of an aromatic sulfonic acid compound or a salt thereof and is soluble in aqueous solvents, and a preparation process thereof.

TECHNICAL FIELD

This invention relates to a sulfo-group-containing heat-resistant highmolecular material which has a high heat resistance and a large specificsurface area and which can be used in a wide variety of fields such asadsorbents, deodorants, filter media and flame retardants.

BACKGROUND ART

Among various high-molecular materials which are industrially useful,carbon materials are excellent generally in such characteristics as heatresistance, corrosion resistance and lubricating property. Further,since they can be imparted with a variety of functions by the adequatecontrol of production conditions and additional treatment conditions,they are being used in various fields as fibers or moldings of desiredshapes depending on the individual use purposes.

Of these carbon materials, fibrous materials are usually produced byheat-treating their precursor fibers to make them infusible, followed bycarbonization and graphitization at higher temperatures. However, thisprocess involves complex production steps and moreover requirescarbonization and graphitization treatments at high temperatures, sothat the resulting carbon materials are relatively expensive andtherefore have had limited uses in spite their excellentcharacteristics. Hence, in the field where high strength orhigh-temperature heat resistance is not particularly demanded, it hasbeen proposed to use fibrous carbon materials in the form of so-calledflame resistant fibers which are not completely carbonized, formed byburning organic fibers at comparatively low temperature.

Further, it has been attempted to introduce sulfo groups into organichigh-molecular materials with a view to imparting functionalities to thematerials. For instance, copolymers of styrene and divinylbenzene havingsulfo groups introduced by means of sulfuric acid, chlorosulfonic acid,etc. have been used as cation exchange resins of strong acid type, andpolystyrenes sulfonated by a similar method have been used as surfaceactive agents. It has also been known to produce fibrous adsorbents byforming side chains, such as styrene, on a base material, such aspolypropylene fiber, by radiation graft copolymerization and sulfonationof the resulting side chains.

It has been reported that among the above-described flame resistantfibers, those of polyacrylonitrile origin contain carbonyl groups ofacridone type, and that active carbon fibers of high hydrogen sulfideadsorptivities can be obtained by activating them at 800°-1,000° C.However, the fibers do not have functionalities, such as absorptivityand ion exchange ability, when they have only undergone a flameresisting treatment of oxidation at 250°-300° C. Sulfonated products ofstyrene-divinylbenzene copolymers are insoluble in water but arepartially soluble in organic solvents such as quinoline and DMSO.Sulfonate polystyrenes are also soluble in water. Moreover, thesesulfonated polymers have low heat resistances of 100° C. or below aswell as low strengths. Further, in the case of radiation graftcopolymers, their preparation has to be done by a particular processusing radiation and, in addition, the heat resistance of the resultingfibers is no more than that of the substrate fibers.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide an industrially usefulhigh-molecular material, which can be prepared by a relatively simpleprocess, which has a high heat resistance and specific surface area,which has no electroconductivity and incorporates high functionalities,such as adsorptivity and deodorizing property, and a preparation processthereof.

The present inventors have made investigations into high-molecularmaterials which have specific functionalities, such as adsorptivity anddeodorizing property, as well as excellent heat resistance and strength,and finally found that a highly functional heat-resistant high-molecularmaterial is obtained by heat-treating a sulfo-group-containing aromatichigh-molecular compound under suitable conditions, leading to completionof the present invention.

The present invention provides a sulfo-group-containing heat-resistanthigh-molecular material containing not less than 1 wt. % of sulfo groupsin terms of sulfur content and having an ammonia adsorptivity of notless than 10 mg/g, formed by heat-treating at a temperature of 250°-500°C. a starting composition composed mainly of a sulfo-group-containingaromatic high-molecular compound which comprises unit constituents of anaromatic sulfonic acid compound or a salt thereof and is soluble inaqueous solvents, and a process for preparing a sulfo-group-containingheat-resistant high-molecular material which comprises heat-treatment ofa methylene type linkage-containing condensation product of an aromaticsulfonic acid compound or a salt thereof in a non-oxidizing atmosphereunder such temperature conditions that the highest temperature is250°-500° C.

The sulfo-group-containing heat-resistant high-molecular material of thepresent invention exhibits high heat resistance which enables thematerial to be used at a temperature in the range of 150°-350° C. aswell as good thermal conductivity and ion exchange capacity. Further, ithas a large specific resistance and also a specific surface area aslarge as 40 m² /g measured by the CO₂ BET method. Therefore, it has goodadsorptivity characteristically, particularly for alkaline componentsincluding ammonia due to the presence of sulfo groups.

As described above, the sulfo-group-containing heat-resistanthigh-molecular material of the present invention incorporates high heatresistance and sufficient strength for practical use as well as highfunctionalities, so that it can be used in a variety of industrialfields as adsorbents, deodorants, filter media, flame retardingmaterials, ion exchangers and heat reserving materials or as componentsfor miscellaneous composite materials.

In particular, it is preferably used as a member required to have heatresistance, corrosion resistance (chemical resistance) and flexibilityas well as non-electroconductivity, that is, as a member to be used inthe area where synthetic resins are insufficient in heat resistance orcarbon materials are inadequate due to their electroconductivity, forexample, as materials for a spacer of electrodes in a fuel cell.

The preparation process of the present invention offers an industriallyadvantageous process for producing materials having the foregoingcharacteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 3 are graphs in each of which an example of variation in aphysical property is illustrated upon heating a starting composition,prepared by forming a formaldehyde condensation product of ammoniumβ-naphthalenesulfonate, into a fibrous material.

FIG. is a graph illustrating the relationship between the heat treatmenttemperature and the contents of carbon, nitrogen and sulfur in thetreated product.

FIG. 2 is a graph illustrating the relationship between the heattreatment temperature and the strength of the treated product.

FIG. 3 is a graph illustrating the relationship between the heattreatment temperature and the specific resistance of the treatedproduct.

BEST MODE FOR CARRYING OUT THE INVENTION

As a raw material for the sulfo-group-containing heat-resistanthigh-molecular material of the present invention, there is used asulfo-group-containing aromatic high-molecular compound with a structurein which unit constituents, each comprising an aromatic sulfonic acidcompound formed by replacing an average of 1 or 2 hydrogen atoms in anaromatic ring such as benzene or naphthalene with a sulfo group or asalt thereof, are linked successively via a certain bonding group.Although there is no particular limitation on the bonding group, it ispreferable to use a bonding group represented by the formula

    --(CH.sub.2).sub.n --T.sub.x --(CHR).sub.m --

wherein T represents a benzene or naphthalene ring, R representshydrogen, a lower alkyl group or a benzene ring, and n, m, and x areindividually an integer of 0 or 1 with the exception that n and m arenot 0 at the same time, from the viewpoint of properties and ease ofproduction and availability. Among others, --CH₂ -- is particularlypreferred. The sulfo-group-containing aromatic high-molecular compound,the raw material used in the present invention, contains an average of 1or 2 sulfo-groups per unit constituent. The sulfo-group-containingaromatic high-molecular compound is usually obtained by thepolymerization or condensation reaction of its unit constituents, eitheralone or together with such bonding group constituents as formaldehyde,paraformaldehyde, hexamethylenetetramine and other aldehydes. However,an increased proportion of a monomer having no sulfo group in the unitconstituents may cause such operational troubles that a gel insoluble inaqueous solvents is formed upon the condensation or polymerizationreaction. Besides, when the average number of sulfo-groups per unitconstituent is less than one, sufficient exhibition of the effects ofthe present invention may not be expected. On the contrary, an increasein the proportion of a monomer containing more than 2 sulfo groups perunit constituent will obstruct the condensation or polymerizationreaction and therefore disturb the production of the high-molecularcompound. Further, when the average number of sulfo-groups per unitconstituent exceeds two, the heat-resistant high-molecular material fromthe final heat treatment will unpreferably be brittle.

As the sulfo-group-containing aromatic high-molecular compound describedabove, it is also possible to use those sulfonated compounds obtained bytreating an aromatic high-molecular compound containing no sulfo groupwith sulfuric acid, chlorosulfonic acid and the like. However, since thesulfo groups are desirably distributed therein as evenly as possible, itis preferable to use sulfo-group-containing aromatic high-molecularcompounds obtained by condensing or polymerizing unit constituents eachcomprising an aromatic sulfonic acid compound. Preferred examples of thehigh-molecular compounds may include those formed by condensingnaphthalenesulfonic acid, anthracenesulfonic acid andphenanthrenesulfonic acid obtained by sulfonating the correspondingaromatic compounds according to the processes known in the art,sulfonated products of a mixture of polycyclic aromatic compounds suchas creosote oil, anthracene oil, tar and pitch, toluenesulfonic acid,xylenesulfonic acid, phenolsulfonic acids, a mixture thereof, or a saltthereof, with formaldehyde, paraformaldehyde, hexamethylenetetramine orother aldehydes; and methylene type linkage-containing polymers such aspolystyrenesulfonic acid obtained by polymerizing an aromatic sulfonicacid having a vinyl group.

As the cation moieties to form the aromatic sulfonates Na⁺, K₊, Ca⁺²,NH₄ ⁺, etc. may be mentioned. Of these sulfonates, ammonium salts arepreferred in view of the ease of handling in heat treatment subsequentto spinning or molding. The preferred salts are dependent on the desiredhigh-molecular materials. For instance, for the production ofhigh-molecular materials requiring high strengths, the ammonium saltsare preferred, whereas in the production of porous adsorbents ordeodorants, the salts of sodium, potassium, iron, calcium, etc. may beused, in addition to the ammonium salts. These sulfo-group-containingaromatic high-molecular compounds can be obtained with a variety ofproperties depending on the kind of aromatic compounds used as the rawmaterial and the conditions of the sulfonation and condensation orpolymerization reactions, and hence can be selectively used at willaccording to the characters of the intended sulfo-group-containingheat-resistant high-molecular materials.

These sulfo-group-containing aromatic high-molecular compounds may beused not only as a single composition but also in the form of a mixtureof two or more of the condensation products, or copolymerization orcopolycondensation products thereof. As an example of thesulfo-group-containing aromatic high-molecular compounds may bementioned a formaldehyde condensation product of ammoniumβ-naphthalenesulfonate, which is a mixture of monomer and variouspolymers having polymerization degrees of up to about 200, and has anumber-average molecular weight of about 800 to 50,000. The condensationproduct is a solid at room temperature, soluble in organic solvents suchas benzene, toluene and acetone at low concentrations and easily solublein aqueous solvents. The 60 wt. % aqueous solution has a viscosity ofabout 10-20,000 poise at 60° C. and has sufficient spinnability andmoldability. The yield in the heat treatment of the condensation productat 250°-500° C. is approximately 95-55 wt. %.

The aforesaid high-molecular compound is only an example of thehigh-molecular compounds to be used in the present invention, and thesort of aromatic sulfonic acid compounds and/or salts thereof determinesthe range of the polymerization (polycondensation) numbers or of thenumber average molecular weights, which specifies thesulfo-group-containing aromatic high-molecular compounds that can beused in the present invention. For example, in the case of thecondensation product of a sulfonated creosote oil, it is common to use amixture of monomer and various polymers having polymerization degrees ofup to 40, whose number average molecular weight is about 2,000 to 5,000,while in the case of the condensation product of phenanthrenesulfonicacid, a mixture of monomer and various polymers having polymerizationdegrees of up to about 30, whose number average molecular weight isabout 2,500 to 5,000, is used. These sulfo-group-containing aromatichigh-molecular compounds are dried and, if necessary, ground and graded,followed by heat treatment or dissolution or dispersion in solvents. Thesolutions or suspensions thus obtained are adjusted in viscosity asrequired, by way of dilution, concentration, etc., and then spun intofibers or molded into any desired forms such as bulky, colmnar, tabular,film-like and honeycomb forms. Thereafter, they are treated with heat toobtain sulfo-group-containing heat-resistant high-molecular materials indesired forms. The solvents used herein may preferably include water,alcohols such as methanol, organic acids such as acetic acid and polarsolvents such as acetonitrile, in view of the characteristics of thesulfo-group-containing aromatic high-molecular compounds. Among others,water or aqueous solvents formed by mixing water and other water-solublesolvents are most suitable.

When fibrous or molded products are to be obtained in the preparationprocess of the present invention, it is useful to add a water-solublehigh-molecular compound in an amount of from 0.02 to 20 parts by weightbased on 100 parts by weight of the starting sulfo-group-containingaromatic high-molecular compound as a spinning or molding auxiliary.Thus, the spinnability or moldability of the starting composition canfurther be improved. The water-soluble high-molecular compounds usedherein are those which are soluble in water or miscellaneous aqueoussolvents, or dispersible therein as colloid. They may preferably includepolyalkylene oxide type compounds such as condensation products ofethylene oxide, propylene oxide, etc. and condensation products of thesecompounds with alcohols, fatty acids, alkylamines or alkylphenols,polyvinyl compounds such as polyvinyl alcohol and polyvinyl pyrrolidone,polyacrylic acid type compounds such as polyacrylic acid,polyacrylamide, acrylic acid-acrylamide copolymers, etc. Among thesulfo-group-containing aromatic high-molecular compounds used as theprincipal raw material in the process of the present invention,polystyrenesulfonic acid and the like, which are highly soluble inwater, may be used as the water-soluble high-molecular compoundmentioned above.

The addition of these water-soluble compounds may effectively acceleratethe rate of spinning, facilitate the handling of spun fibers or moldingsprior to the heat treatment, and increase the strength of the resultingfibrous or molded high-molecular materials. When the amount of thewater-soluble high-molecular compound added exceeds 20 parts by weight,an additional infusibilizing step will unfavorably be necessary becausethe fibers or the like are liable to fuse upon raising temperature orheating during the heat treatment.

Since the sulfo-group-containing aromatic high-molecular compounds usedas a raw material in the preparation process of the present inventioncan be heat-treated without need for a prior infusibilizing treatment,they are particularly suitable for use in the production of fibrousheat-resistant high-molecular materials.

The starting composition composed mainly of the sulfo-group-containinghigh-molecular compound is subjected to heat treatment as granules orafter being formed into fibrous or other desired shapes. The heattreatment is conducted by heating the composition in a non-oxidizingatmosphere in such a range that the highest temperature attains250°-500° C, preferably 350°-400° C. Upon heating the startingcomposition, elimination of the sulfo groups begins to take place at atemperature in the vicinity of 250° C, and the starting composition,that is soluble in solvents such as water, is converted into ahigh-molecular material that is insoluble in the solvents, infusible andhas strength enough to withstand handling as well as a high specificsurface area and adsorptivity.

It is assumed that during the heat treatment, three dimensionalcrosslinking and improvement of surface properties proceed following theelimination of volatile matter, and the presence of the sulfo groupspromotes these proceedings.

The variations of the physical properties upon heating the startingcomposition, composed mainly of the sulfo-group-containing aromatichigh-molecular compound, are as illustrated in FIGS. 1 to 3, typicallywith respect to a starting composition of fibrous form prepared from aformaldehyde condensation product of ammonium β-naphthalenesulfonate. Aswill be discussed below, since the chemical reaction taking place uponheating is endothermic and the variations of the physical properties arehardly affected by the rate of raising temperature, the drawings aregiven in terms of the relationship between the temperature of the heattreatment or carbonization and each of the physical properties.

FIG. 1 is a graph illustrating the variations of the contents of carbon,nitrogen and sulfur in the material. As seen in the graph, the contentsof carbon, nitrogen and sulfur in the material become practicallyconstant at a heat treatment temperature of between 600° and 700° C.,and further heating causes a gradual increase of carbon and a gradualdecease of nitrogen and sulfur owing to the progress of carbonization.

FIG. 2 shows the variations of strength caused by heat treatment,illustrating that the exhibition of strength of the material occurs intwo stages. The first stage takes place primarily with the progress ofthree dimensional crosslinking in heat treatment at 300°-500° C., whilethe second stage is exhibited by carbonization above 600°-700° C.

FIG. 3 is a graph showing the variation of specific resistance with heattreatment temperature. From this drawing, it is found that sincecarbonization does not take place in heat treatment below 600° C., theresulting material is a non-conductor with little ability of conductingelectricity, but by heating above 700° C., carbonization proceeds totransform the material to a good conductor.

As described above, the properties of the material obtained byheat-treating a sulfo-group-containing aromatic high-molecular compoundvary significantly at around 600° C. The heat-resistant high-molecularmaterials of the present invention which are formed by heat-treatmentbelow 500° C exhibit the properties of organic matter and hence differfrom the carbides obtained by heat treatment at higher temperature.

Further, the heating up to 400° C. of the starting composition conductedin an oxygen-containing atmosphere accelerates the formation offunctional groups such as carbonyl and carboxyl on the surface of thematerial, thus efficiently imparting the material such functionalitiesas adsorptivity and deodorizing property.

The optimum heat treatment conditions vary with the properties of thestarting composition and the desired sulfo-group-containingheat-resistant high-molecular material. However, they may properly bedetermined in such a way that the highest temperature lies between 250°C. and 500° C. and the product still holds 10-90% of the sulfo groupscontained in the starting composition and hence contains sulfo groups inan amount of not less than 1 wt. % in terms of sulfur content. If thehighest temperature is less than 250° C., the heat treating effects willbe insufficient and strength will also be undesirably low. If thestarting composition is heat-treated beyond 400° C. in anoxygen-containing atmosphere or beyond 500° C. even in a non-oxidizingatmosphere, the strength of the product increases. However, most of thesulfo groups contained in the starting composition are stripped offduring heat-treatment, and the product does not exhibit thecharacteristic effects of sulfo groups.

The chemical reaction in the heat treatment step of the presentinvention is endothermic and hence does not impose any particularlimitations on the rate of raising temperature during heat treatment.However, when the water formed by thermal decomposition attaches to thestarting composition, the composition becomes liable to partialdissolution, adhesion, deformation, etc. Therefore, it is desirable tocarry out the heat treatment under conditions capable of rapid removalof the thermal decomposition gas, for example, in a stream of a carriergas or under reduced pressure.

When a fibrous product is produced, it is effective for the improvementof strength to exert a tensile force on the composition during heattreatment.

The sulfo-group-containing heat-resistant high-molecular materials ofthe present invention are those containing sulfo groups in an amount ofnot less than 1 wt. % in terms of sulfur content, having a specificsurface area of not less than 40 m² /g measured by the CO₂ BET method,having an ammonia adsorptivity of not less than 10 mg/g, and which donot cause substantial weight reduction up to 250° C. They are lustrous,yellow or black, highly heat-resistant and corrosion-resistant(chemical-resistant) high-molecular materials. Another characteristic ofthe sulfo-group-containing heat-resistant high-molecular material isthat its electric conductivity is low owing to its large specificresistance of 10⁸ Ω·cm. These characteristics make it possible toprovide a material which requires a high heat resistance up to 250° C.and corrosion resistance and is suitable for members that should nothave electric conductivity. It is also possible to impart flexibility tothe material by forming it into a fibrous product. However, when as theraw material a salt of aromatic sulfonic acids is used, the cationicmoiety of which does not volatilize during heat treatment, e.g., a Nasalt, the resultant material sometimes has a hygroscopic property andexhibits lower specific resistance due to the water adsorbed. Thesephysical properties vary in accordance with the kind of startingcompositions, heat treatment conditions, shape of the products, etc. Anexample of the fibrous products teaches that the strength increases witha rise in heat treatment temperature, giving a value of 15-50 kg/mm² byheat treatment at 350°-450° C. in a stream of nitrogen. The specificsurface area of the fibers also increases with increasing heat treatmenttemperature, giving a value of 50-200 m^(2/) g for a 350°C.-heat-treated product and approximately 250 m^(2/) g for a 450°C.-heat-treated product, as measured by the CO₂ BET method.

The present invention will be illustrated more specifically withreference to the following examples.

EXAMPLE 1

To 1,280 g of refined naphthalene was added 1050 g of 98% sulfuric acid,and the naphthalene was sulfonated by reaction at 155° C. for 3 hours.The resulting mixture was distilled under reduced pressure to removefrom the system the unreacted naphthalene and the water formed by thereaction. The composition of the sulfonated product was:β-naphthalenesulfonic acid=96.2 wt. %; α-naphthalenesulfonic acid=notdetected; naphthalenepolysulfonic acid=3.0 wt. %; and unreactednaphthalene=0.8 wt. %. Thereafter, the sulfonated product was combinedwith 1,000 ml of water and then with 857 g of 35% aqueous formaldehyde.They were reacted at 105° C. for 8 hours and neutralized with ammonia.Insoluble matter was separated therefrom by filtration and the filtratewas concentrated to obtain an aqueous solution of a formaldehydecondensation product of β-naphthalenesulfonic acid with a number averagemolecular weight of 3,820, the solution containing 45 wt. % of water andhaving a viscosity of 1,000 poise at 32° C.

The aqueous solution as a raw material was subjected to dry spinningusing a spinneret of 0.1 mm in diameter. The resulting spun fiber wasput in a vessel at a bulk density of 0.025 g/cm³, charged in a furnacekept at 250° C., and raised in temperature in a stream of nitrogen at arate of 20° C./min to a predetermined temperature, at which it was keptfor a predetermined period of time for its heat treatment. Theproperties of the heat-treated products thus obtained are given in Table1.

The 375° C.-heat-treated product given in Table 1 was allowed to adsorbammonia, then to desorb the ammonia at 180° C, and to adsorb ammoniaagain at room temperature. Ammonia was adsorbed therein in an amount of34.3 mg/g. The same sample was then allowed to desorb the ammonia at250° C., and to adsorb ammonia again, with the result that 34.9 mg/g ofammonia was adsorbed. Thus, it was found that repeated use of theproducts was feasible by heat regeneration.

                                      TABLE 1                                     __________________________________________________________________________    Properties of Heat-treated Products                                                                                    Bunde static                         Heat treating          Fiber                                                                             Surface area  method NH.sub.3                      conditions   Tensile                                                                             Elon-                                                                             di- N.sub.2 BET                                                                        CO.sub.2 BET                                                                       Sulfur                                                                            adsorptn.                                                                            Solubility                                                                             Specific             Temp.    Time                                                                              strength                                                                            gation                                                                            ameter                                                                            method                                                                             method                                                                             content                                                                           room temp.                                                                           to   Color                                                                             resistance           (°C.)                                                                           (min)                                                                             (kg/mm.sup.2)                                                                       (%) (μm)                                                                           (m.sup.2 /g)                                                                       (m.sup.2 /g)                                                                       (wt %)                                                                            (mg/g) water                                                                              tone                                                                              (Ω                                                                      ·           __________________________________________________________________________                                                             cm)                  Raw   25 --  2.40  14.8                                                                              30            13.5       Soluble                                                                            yellow                   material                                                                      Example                                                                            255 120 7.20  12.8                                                                              28  0.6   82  6.2 42.4   insoluble                                                                          black                                                                             10.sup.8 or                                                                   more                      325 1   8.98  12.7                                                                              27  0.3   62  6.6 49.9   "    "   "                         350 0.5 24.9  11.4                                                                              25  1.0   80  5.2 38.4   "    "   "                         375 0.5 28.4  8.9 24  0.8  113  2.7 36.5   "    "   "                         400 0.25                                                                              31.4  8.8 23  0.7  214  4.2 23.9   "    "   "                         450 0.25                                                                              31.5  6.7 23            2.4        "    "   "                         500 0.25                                                                              32.2  6.7 22  1.0  210  1.3 16.3   "    "   "                    Refer-                                                                             600 0.02                                                                              19    4.6 34.0          0.8        "    "   6.1 ×                                                                   10.sup.7             ence 700 0.02                                                                              19    4.0 52.0                                                                              2.2  225  0.7 6.2    "    "   5.3 ×                                                                   10.sup.4             Example                                                                       __________________________________________________________________________

EXAMPLE 2

To 1,420 g of naphthalene oil (composition: a lower boiling distillatethan naphthalene boiling point=4.2 wt. %; naphthalene=28.4 wt. %;β-methylnaphthalene=49.0 wt. %; α-methylnaphthalene=12.1 wt. %; anintermediate boiling distillate between naphthalene andα-methylnapthahlene=4.0 wt. %; and a higher boiling distillate thanα-methylnaphthalene boiling point=4.3 wt. %) was added 1,200 g of 98%sulfuric acid. The naphthalene oil was sulfonated by reaction at 150° C.for 3 hours. The resulting mixture was distilled under reduced pressureto remove from the system the unreacted oil and the water formed by thereaction. Thereafter, the sulfonated oil was combined with 500 g ofwater and then with 857 g of 35% aqueous formaldehyde. They were reactedat 105° C. for 15 hours, and then calcium hydroxide was added thereto inan amount of 0.9-equivalent to the residual sulfuric acid, therebyremoving the sulfuric acid as gypsum by filtration. The filtrate wasneutralized with ammonia and subjected to evaporation at 105° C. for 2hours. Based on the solid residue thus obtained, 0.5 wt. % ofpolyethylene glycol (manufactured by Seitetsu Chemical Industries Co.,Ltd.; trade name: PEO-3; average molecular weight: 600,000-1,100,000)was added as an aqueous solution. The resultant mixture was adjusted inwater content to obtain a starting composition containing 38 wt. % ofwater and having a viscosity of 10,000 poises at 80° C., the compositionbeing composed mainly of a formaldehyde condensation product ofsulfonated naphthalene oil, the solid matter of which compositioncontains 13.6 wt. % of sulfo groups in terms of sulfur content. Thestarting composition was subjected to an extruder at 80° C. to form itinto a honeycomb-shaped molded article. The molded article was thenraised in temperature at a rate of 10° C./min in a stream of air under areduced pressure of 50 Torr from room temperature to 375° C., at whichit was kept for 15 minutes for its heat treatment.

The honeycomb molded article thus obtained was black and contained 4.4wt. % of sulfo groups in terms of sulfur content. It was insoluble insolvents and infusible and had a surface area of 1.0 m² /g according tothe N₂ BET method and that of 75 m² /g according to the CO₂ BET method.Its adsorption of ammonia was 35 mg/g, while the specific resistance was10⁸ Ω·cm or more, at room temperature.

The honeycomb molded article was immersed in a 1 wt. % aqueous NaClsolution in an autoclave and treated under the conditions of 20atmospheres and 150° C. Its ion exchange capacity was measured to be 2.4meq/g, showing good performance as an ion exchanger.

EXAMPLE 3

The 325° C.-heat-treated black fiber obtained in Example 1 was packed ina 120×40×40 mm mold at a density of 0.136 g/cm³ and treated with heatfor 5 minutes in a furnace at 350° C. The resulting molded article was arectangular parallelopiped with dimensions of 120×40×38 mm and a densityof 0.134 g/cm³ and contained 5.2 wt. % of sulfo groups in terms ofsulfur content. Its heat conductivity was 0.045 W/m·k, exhibiting goodthermal conduction, while the specific resistance was 10⁸ Ω·cm or more.

We claim:
 1. A sulfo-group-containing heat-resistant high-molecularmaterial containing sulfo groups in an amount of not less than 1 wt. %in terms of sulfur content and having an ammonia adsorptivity of notless than 10 mg/g, formed by heat-treating at a temperature of 250°-500°C. a starting composition composed mainly of a sulfo-group-containingaromatic high-molecular compound which comprises unit constituents of anaromatic sulfonic acid compound or a salt thereof and is soluble inaqueous solvents.
 2. A fibrous sulfo-group-containing heat-resistanthigh-molecular material containing sulfo groups in an amount of not lessthan 1 wt. % in terms of sulfur content and having an ammoniaadsorptivity of not less than 10 mg/g, formed by adjusting the viscosityof an aqueous solvent solution of a starting composition composed mainlyof a sulfo-group-containing aromatic high-molecular compound whichcomprises unit constituents of an aromatic sulfonic acid compound or asalt thereof and is soluble in aqueous solvents, spinning the resultingsolution into a fibrous material, and heat-treating the fibrous materialat a temperature of 250°-500° C.
 3. A fibrous sulfo-group-containingheat-resistant high-molecular material containing sulfo groups in anamount of not less than 1 wt. % in terms of sulfur content and having anammonia adsorptivity of not less than 10 mg/g and a specific resistanceof not less than 10⁸ Ω·cm, formed by adjusting the viscosity of anaqueous solvent solution of a starting composition composed mainly of asulfo-group-containing aromatic high-molecular compound which comprisesunit constituents of an ammonium salt of an aromatic sulfonic acidcompound and is soluble in aqueous solvents, spinning the resultingsolution into a fibrous material and heat-treating the fibrous materialat a temperature of 250°-500° C.
 4. A molded sulfo-group-containingheat-resistant high-molecular material containing sulfo groups in anamount of not less than 1 wt. % in terms of sulfur content and having anammonia adsorptivity of not less than 10 mg/g, formed by adjusting theviscosity of an aqueous solvent solution of a starting compositioncomposed mainly of a sulfo-group-containing aromatic high-molecularcompound which comprises unit constituents of an aromatic sulfonic acidcompound or a salt thereof and is soluble in aqueous solvents, moldingthe resulting solution and heat-treating the molded article at atemperature of 250°-500° C.
 5. A process for preparing thesulfo-group-containing heat-resistant high-molecular material accordingto any one of claims 1 through 4, which comprises heat-treating astarting composition composed mainly of a methylene typelinkage-containing condensation product of an aromatic sulfonic acidcompound or a salt thereof in a non-oxidizing atmosphere under such atemperature condition that the highest temperature is 250°-500° C.
 6. Aprocess for preparing the sulfo-group-containing heat-resistanthigh-molecular material according to any one of claims 1 through 4,which comprises heat-treating a starting composition composed mainly ofa methylene type linkage-containing condensation product of an aromaticsulfonic acid compound of a salt thereof in an oxygen-containingatmosphere under such a temperature condition that the highesttemperature is 250°-400° C. and then, if necessary, heat-treating theresulting composition in a non-oxidizing atmosphere under such atemperature condition that the highest temperature is 250°-500° C. 7.The process for preparing the sulfo-group-containing heat-resistanthigh-molecular material according to claim 5 wherein a mixture obtainedby adding 0.02-20 parts by weight of a water-soluble high-molecularcompound to 100 parts by weight of the methylene type linkage-containingcondensation product of an aromatic sulfonic acid compound or a saltthereof is used as the starting material.
 8. The process for preparingthe sulfo-group-containing heat-resistant high-molecular materialaccording to claim 5 wherein the heat treatment is carried out underreduced pressure.
 9. The process for preparing thesulfo-group-containing heat-resistant high-molecular material accordingto claim 6 wherein a mixture obtained by adding 0.02-20 parts by weightof a water-soluble high-molecular compound to 100 parts by weight of themethylene type linkage-containing condensation product of an aromaticsulfonic acid compound or a salt thereof is used as the startingmaterial.
 10. The process for preparing the sulfo-group containingheat-resistant high-molecular material according to claim 6 wherein theheat treatment is carried out under reduced pressure.
 11. The processfor preparing the sulfo-group-containing heat-resistant high-molecularmaterial according to claim 7 wherein the heat treatment is carried outunder reduced pressure.